<template>
	<scroll-view scroll-y style="height: 240rpx;width: 100%;" :scroll-top="scrollTop" @scroll="handleScroll">
		<movable-area style="height: 100%;width: 100%;">
			<movable-view v-for="(item, index) in list" :animation="animation" :direction="direction" :key="item.key"
				:damping="damping" :x="item.x" :y="item.y" :disabled="longpress ? disabled : false"
				@longpress="handleLongpress" @touchstart="handleDragStart(index)" @change="handleMoving"
				@touchend="handleDragEnd" style="height: 60rpx;" :class="{ active: activeIndex === index }"
				@click="deleteLabel(index)">
				<view class="drag-item" :style="{justifyContent: index == 0 ? 'flex-start' : 'center'}">
					<text v-if="index == 0"
						style="width:60rpx;float:left;background:#FF6600;border-radius:15rpx 0 0 15rpx;flex: 1;color: #fff;font-size: 22rpx;">主</text>
					<text style="white-space: nowrap;overflow: hidden;text-overflow: ellipsis;"
						:style="{marginLeft: index == 0 ? '5rpx' : '', flex: index == 0 ? '3' : ''}">{{ item[itemKey] }}</text>
				</view>

			</movable-view>
		</movable-area>
	</scroll-view>
</template>

<script>
	export default {
		props: {
			column: {
				type: Number,
				default: 3
			},
			value: {
				type: Array,
				default: () => []
			},
			width: {
				type: String,
				default: '100%'
			},
			height: {
				type: String,
				default: 'auto'
			},
			itemKey: {
				type: String,
				required: true
			},
			itemHeight: {
				type: String,
				default: '100px'
			},
			direction: {
				type: String,
				default: 'all',
				validator: value => {
					return ['all', 'vertical', 'horizontal', 'none'].includes(value);
				}
			},
			animation: {
				type: Boolean,
				default: true
			},
			damping: {
				type: Number,
				default: 20
			},
			longpress: {
				type: Boolean,
				default: true
			}
		},
		data() {
			return {
				list: [],
				disabled: true,
				activeIndex: -1,
				moveToIndex: -1,
				oldIndex: -1,
				tempDragInfo: {
					x: '',
					y: ''
				},
				cloneList: [],
				scrollTop: 0
			};
		},
		computed: {
			// getScrollStyle() {
			// 	const width = this.getRealWidth(this.width);
			// 	return { height: this.height };
			// },
			getAreaStyle() {
				const width = this.getRealWidth(this.width);
				return {
					height: Math.ceil(this.list.length / this.column) * this.getItemHeight + 'px'
				};
			},
			// getViewStyle() {
			// 	const { itemHeight, getItemWidth } = this;
			// 	return { width: getItemWidth + 'px', height: itemHeight };
			// },
			getItemHeight() {
				return parseFloat(this.itemHeight);
			},
			getItemWidth() {
				if (this.column === 0) return;
				const width = this.getRealWidth(this.width);
				return (parseFloat(width) / this.column).toFixed(2);
			}
		},
		methods: {
			deleteLabel(index) {
				// console.log(this.list[index])
				this.list[index].selected = false; // 删除
				this.$emit('deleteLabel', index)
				this.list.splice(index, 1);
			},
			//获取实际的宽度
			getRealWidth(width) {
				if (width.includes('%')) {
					const windowWidth = uni.getSystemInfoSync().windowWidth;
					width = windowWidth * (parseFloat(width) / 100);
				}
				return width;
			},

			initList(list = []) {
				const newList = this.deepCopy(list);
				this.list = newList.map((item, index) => {
					const [x, y] = this.getPosition(index);
					return {
						...item,
						x,
						y,
						key: Math.random() + index
					};
				});
				this.cloneList = this.deepCopy(this.list);
			},

			//长按
			handleLongpress() {
				this.disabled = false;
			},

			//拖拽开始
			handleDragStart(index) {
				this.activeIndex = index;
				this.oldIndex = index;
			},

			//拖拽中
			handleMoving(e) {
				if (e.detail.source !== 'touch' || this.disabled) return;
				const {
					x,
					y
				} = e.detail;
				Object.assign(this.tempDragInfo, {
					x,
					y
				});
				const currentX = Math.floor((x + this.getItemWidth / 2) / this.getItemWidth);
				const currentY = Math.floor((y + this.getItemHeight / 2) / this.getItemHeight);

				this.moveToIndex = Math.min(currentY * this.column + currentX, this.list.length - 1);

				if (this.oldIndex !== this.moveToIndex && this.oldIndex !== -1 && this.moveToIndex !== -1) {
					const newList = this.deepCopy(this.cloneList);
					newList.splice(this.moveToIndex, 0, ...newList.splice(this.activeIndex, 1));

					this.list.forEach((item, index) => {
						if (index !== this.activeIndex) {
							const itemIndex = newList.findIndex(val => val[this.itemKey] === item[this.itemKey]);
							[item.x, item.y] = this.getPosition(itemIndex);
						}
					});
					this.oldIndex = this.moveToIndex;
					this.scrollIntoView();
				}
			},

			//获取当前的位置
			getPosition(index) {
				const x = (index % this.column) * this.getItemWidth;
				const y = Math.floor(index / this.column) * this.getItemHeight;
				return [x, y];
			},

			//拖拽结束
			handleDragEnd(e) {
				if (this.disabled) return;
				if (this.moveToIndex !== -1 && this.activeIndex !== -1 && this.moveToIndex !== this.activeIndex) {
					this.cloneList.splice(this.moveToIndex, 0, ...this.cloneList.splice(this.activeIndex, 1));
				} else {
					this.$set(this.list[this.activeIndex], 'x', this.tempDragInfo.x);
					this.$set(this.list[this.activeIndex], 'y', this.tempDragInfo.y);
				}
				this.initList(this.cloneList);
				const endList = this.list.map(item => this.omit(item, ['x', 'y', 'key']));
				this.$emit('input', endList);
				this.$emit('end', endList);

				this.$emit('handleEnd', this.list);

				this.activeIndex = -1;
				this.oldIndex = -1;
				this.moveToIndex = -1;
				this.disabled = true;
			},

			scrollIntoView() {
				if (this.height === 'auto') return;
				const {
					height,
					moveToIndex,
					getItemHeight,
					scrollTop
				} = this;

				if ((moveToIndex + 1) * this.getItemHeight >= scrollTop + parseFloat(height)) {
					this.scrollTop = Math.min(parseFloat(this.getAreaStyle.height), scrollTop + Math.ceil(moveToIndex /
						2) * this.getItemHeight);
				} else if ((moveToIndex - 1) * this.getItemHeight <= scrollTop) {
					this.scrollTop = Math.max(0, scrollTop - Math.ceil(moveToIndex / 2) * this.getItemHeight);
				}
			},

			setScrollTop(index) {
				this.scrollTop = index * this.getItemHeight;
			},

			handleScroll(e) {
				this.scrollTop = e.detail.scrollTop;
			},

			deepCopy(source) {
				return JSON.parse(JSON.stringify(source));
			},

			/**
			 * 排除掉obj里面的key值
			 * @param {object} obj
			 * @param {Array|string} args
			 * @returns {object}
			 */
			omit(obj, args) {
				if (!args) return obj;
				const newObj = {};
				const isString = typeof args === 'string';
				const keys = Object.keys(obj).filter(item => {
					if (isString) {
						return item !== args;
					}
					return !args.includes(item);
				});

				keys.forEach(key => {
					if (obj[key] !== undefined) newObj[key] = obj[key];
				});
				return newObj;
			}
		},
		watch: {
			value: {
				handler() {
					this.initList(this.value);
				},
				immediate: true,
				deep: true
			}
		}
	};
</script>

<style lang="scss" scoped>
	.drag-item {
		float: left;
		background-color: #FFDD00;
		color: #000;
		width: 187rpx;
		text-align: center;
		border-radius: 15rpx;
		height: 60rpx;
		line-height: 60rpx;
		display: flex;
		flex-direction: row;
		align-items: center;
	}
</style>